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. 2014 Oct 15;8:807. doi: 10.3389/fnhum.2014.00807

Table 1.

Overview of neuroimaging studies using virtual characters to study non-verbal behavior processing in HFA.

Study Participant characteristics Experimental design and stimuli Description of results
Pelphrey et al. (2005)

fMRI

Eye gaze direction (congruency)		 N = 10 ASD (mean age: 23.2), right-handed; compared to other studies conducted in his laboratory Stimuli: short videos of a VC shifting their gaze either congruently or incongruently with the location of an appearing checkerboard

Design: 10 runs (70 trials of each condition); eye tracking

Task: attend to the screen at all times, but allowed to look at presented stimulus in any way the wish; press a button with right or left thumb when eye movement is seen, no matter whether the eyes acquire the target		 Behavioral:

  1. Eye tracking showed no differences  between subjects with and without ASD

Neural:

  1. Subjects in autism do not show differences  in activity of the STS and other  brain regions linked to social cognitions

  2. Activity in these regions was not modulated  by the context of the perceived gaze shift
Pitskel et al. (2011)

fMRI

Eye gaze direction (direct vs. averted)		 N = 15 male HFA (mean age: 23.4) and 14 matched controls (mean age 24.2) Stimuli: an approaching male VC maintained either direct or averted gaze with the observer

Design: one run (422 s), 10 trials (6 s per trial) intertrial intervals of 12, 14, or 16 s

Task: attend to the displays and remain alert and awake		 Behavioral:

  1. Both participant groups were sensitive to the  experimental manipulation, yet the gaze  condition that elicits preferential neural  activation differs as a function of group status

Neural:

  1. TD: greater activation to direct gaze in the  right anterior insula (AI), bilateral caudate, left  thalamus, left cerebellum, and left inferior  frontal gyrus

  2. HFA: greater activation to direct gaze in left  cuneus, and greater activation to averted gaze  in bilateral cerebellum and left inferior occipital  gyrus. No correlations between activation  in regions modulated by gaze condition  correlated significantly with age or Full  Scale IQ
Right AI only showed significant differences between gaze in the typically developing group, while left LOC was only significantly modulated by gaze in the autism group
Schulte-Rüther et al. (2011)

fMRI

Emotional facial expression recognition		 N = 18 male ASD (mean age: 27.40) and 18 matched controls; only 14 of each group included in final fMRI (ASD group: 7 AS, 7 HFA) Stimuli: three dimensional representations made of male faces, morphed to happy or sad expression (each with how or low intensity) or neutral expression (2 × 2 × 2 and 3 × 2); static

Design: block design; 12 blocks with three experimental tasks, each block consisting of 6 trials (total of 192 trials)

Task: identify emotional expression of face (other) or emotion elicited in themselves by the face (self)		 Behavioral:

  1. Reaction times were faster for the other- than  for the self-task and faster for the high than  the low emotion intensity stimuli

  2. Number of correct responses for the  other-task was higher than the number of  congruent responses for the self-task and  higher for the high emotional intensity than  the low emotional intensity stimuli

Neural:

  1. Other-task vs. control task: control  subjects showed differential activation in  the vMPFC and precuneus/PCC, subjects  with autism showed differential activation in  the dMPFC

  2. Self-task vs. control task: control subjects  showed additional activations in the dMPFC,  left IFC, left TPJ, and right

  3. Cerebellum, subjects with ASD showed  increases in activity of left superior frontal  gyrus, bilateral middle frontal gyrus, bilateral  IFC, bilateral TPJ, ITG and temporal pole

  4. Conjunction of other task vs. control task and  self-task vs. control task: in ASD subjects,  conjoint activation could be observed in  bilateral precuneus/PCC and left dMPFC
Georgescu et al. (2013)

fMRI, eye tracking

Eye gaze direction (direct vs. averted) and duration		 N = 13 HFA (9 male, mean age:31.23) and 13 matched controls (9 male, mean age: 30.23) Stimuli: ca. 5 s animations of 10 male and 10 female VC neutral faces, displaying either averted or direct gaze of varying duration (1, 2.5, 4 s)

Design: 2 × 3, parametric; event-related; factor (1) gaze direction (direct and averted) and factor (2) gaze duration (1, 2.5, 4 s)

Task: judging likeability of each VC on a 4-point scale		 Behavioral:

  1. HFA participants showed no significant  difference in likeability ratings depending on  gaze duration

  2. Control group rated the virtual characters as  increasingly likeable with increasing gaze  duration

  3. No significant group difference

Eye tracking: no difference in fixation on any face ROI across conditions and across groups
Neural:

  1. In controls: Regions of the SNN are activated  by direct vs. averted gaze and by increasing  gaze duration perception

  2. In HFA: the pSTS is activated by direct  compared to averted gaze; no differential  activation for processing increasing gaze  duration: regions of the SNN are engaged by  averted compared to direct gaze and by  decreasing gaze duration
von dem Hagen et al. (2013)

fMRI, eye tracking

Eye gaze direction (direct vs. averted)		 N = 21 male HFA and AS (mean age: 29) and 25 matched controls (mean age: 26) Stimuli: animations of 5 male and 5 female VC neutral faces, displaying either averted or direct gaze

Design: block design 21-s long epochs

Task: gender judgments		 Neural:

  1. No group differences in DMNb, DMNc,  salience, and MTL networks within or without  ROIs

  2. Significantly reduced functional connectivity  between and within resting state networks